Switchgear

ABSTRACT

The instrumentation transformers  6   a  to  6   d  and  7   a  to  7   f  for measuring the voltage of the main circuit are arranged within the container  15   b  located in the midst of the containers  15   a  to  15   c.  In the present invention, the containers  15   a  and  15   b  are linked by the insulating tube  21   a  and the primary-side lead lines  49  and  53  connected electrically to the primary-side terminal of the instrumentation transformers  6   a  and  7   a  are made routed from the container  15   b  through the insulating tube  21   a  to the container  15   a,  and the containers  15   b  and  15   c  are linked by the insulating tube  21   b  and the primary-side lead lines  51  and  55  connected electrically to the primary-side terminal of the instrumentation transformers  6   d  and  7   e  are made routed from the container  15   b  through the insulating tube  21   b  to the container  15   c.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a substation component for thepower generator installed in the power plants such as thermal electricpower plants, nuclear power plants and hydro-electric power plants,especially to a switchgear installed on the main circuit from thegenerators to the transformers.

[0002] As for the switchgear installed on the main circuit from thegenerators to the transformers, for example, what is well known isdisclosed in Japanese Patent Laid-Open Number 61-1218 (1986). Theswitchgear disclosed in this document is composed so that the componentsfor the individual phases are separated and the switchgears arecontained in the individual exterior covering, respectively. Theupper-side of the exterior covering containing the switchgear isconnected through the exterior covering containing the connecting bustie to the exterior covering containing the disconnecting switch instep-wise configuration.

[0003] In this kind of conventional switchgear, the contact makers ofthe breaker part of the disconnecting switch are made contact to andleave from each other in responsive to the voltage value in the maincircuit. In order to measure the voltage value in the main circuit,plural instrumentation transformers are installed at the switchgears.Those instrumentation transformers are installed in separate containersother than the containers containing the breaker part of thedisconnecting switch.

[0004] In recent years, many efforts are made for integrating componentsinto a unified and composite unit in order to downsize the switchgearsand reduce their cost. Along with this trend, there arises strongrequest to accommodate plural instrumentation transformers in thecontainer including the breaker part of the disconnecting switches.However, there are still unsolved problems regarding the method for thelayout of plural instrumentation transformers in three containersarranged together.

SUMMARY OF THE INVENTION

[0005] A major object of the present invention is to provide aswitchgear enabling to increase the working efficiency for theinstallation operation of the instrumentation transformers into thecontainers and the withdrawal operation of the instrumentationtransformers from the containers.

[0006] The present invention is characterized by such an arrangement ofplural instrumentation transformers for measuring the voltage in themain circuit as located within the container in the midst of containersarranged together.

[0007] According to the above described embodiment, as pluralinstrumentation transformers are arranged within the container locatedin the midst of the center among the containers arranged together, theinstallation operation of the instrumentation transformers into thecontainers and the withdrawal operation of the instrumentationtransformers 6 a to 6 d from the containers may be applied only to thecontainer 15 b, and the installation and withdrawal operation at theother containers may be done simply by wiring the primary-side leadlines. Owing to this configuration, the work load and work time for theinstallation operation of the instrumentation transformers 6 a to 6 dinto the containers and the withdrawal operation the instrumentationtransformers 6 a to 6 d from the containers can be reduced to a largeextent.

[0008] According to the present invention, it is easy to route theprimary-side lead line of the instrumentation transformer from thecontainer located a the center to the containers located at both ends.That is, in case that the instrumentation transformers are installed inthe containers located at both ends, there occurs a part in which acouple of primary-side lead lines for the instrumentation transformersare required to be routed. As it is necessary to establish an enoughinsulation distance between two lead lines in this configuration, thestructure of routing the primary-side lead lines may be complicated orthe container may be upsized. In contrast, in this invention, as pluralinstrumentation transformers are arranged within the container locatedin the midst among the containers, the primary-side lead lines for theinstrumentation transformers can be accommodated by a single cableextended from the container located in the midst to the containerslocated at both ends. Thus, it will be appreciated that the complexityin the routing configuration for the primary-side lead lines and theupsizing of the containers can be reduced.

[0009] A couple of coadjacent containers among three containers arrangedtogether are linked by an insulating tube. The primary-side lead line ofthe instrumentation transformer corresponding to the phase for thecontainers located at both ends of three containers arranged together ismade routed from the container located in the midst among threecontainers through the insulating tube to the corresponding containerlocated at one of both ends of containers. The reason why the insulationtube is used for linking the containers is to prevent the cyclic currentfrom flowing between the containers.

[0010] A breaker part of the disconnecting switch for disconnectingelectrically the main circuit is installed at the individual containersarranged together. The breaker part is insulated by the insulating gassuch as sulfur hexafluoride, and has a contact makers operated by themanipulator so as to contact to and leave from each other. A switchingpart of the disconnecting switch, a switching part of the earthingswitch and an arrestor, connected electrically to the main circuit, arearranged in three containers arranged together, individually.

[0011] The height of the container located in the midst among threecontainers arranged together is made larger than the height of the othercontainers in order to establish an enough insulation distance betweenplural instrumentation transformers and the other components. Theprimary-side of plural instrumentation transformers is configured withopen-delta connection or star connection. The plural instrumentationtransformers are supported so as to be suspended down from the ceilingboard installed above the container. The arresters are also supported soas to be suspended down from the ceiling board installed above thecontainer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a cross-sectional drawing illustrating the structure ofthe switchgear as the first embodiment of the present invention.

[0013]FIG. 2 is a cut-away drawing at the line II-II of FIG. 1.

[0014]FIG. 3 is a cut-away drawing at the line III-III of FIG. 1.

[0015]FIG. 4 is a three-phase connection diagram of the switchgear asthe first embodiment of the present invention.

[0016]FIG. 5 is a cross-sectional drawing illustrating the structure ofthe switchgear as the second embodiment of the present invention.

[0017]FIG. 6 is a cut-away drawing at the line III-III of FIG. 5.

[0018]FIG. 7 is a three-phase connection diagram of the switchgear asthe second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] By referring to attached figures, the embodiment of the presentinvention is disclosed.

[0020]FIG. 4 shows a three-phase connection diagram of the switchgear inthe first embodiment of the present invention. The switchgear of thisembodiment is a substation component for the power generator installedin the power plants such as thermal electric power plants, nuclear powerplants and hydro-electric power plants, which is used for breaking theheavy current in the main circuit from the power generator to thetransformers. This switchgear comprises separated components for theindividual phases, U-phase, V-phase and W-phase, respectively.

[0021] Incidentally, in the hypo-description, in case where thearrangements of the phases of three are the same, in order to avoidreduplicated description, any one of the phases of three (the U-phase inthe hypo-description on the present embodiments) is typically explained.Corresponding reference characters of the other phases are shown inparenthesis, and the explanation of there arrangements is omitted.

[0022] A component 1 a (1 b, 1 c) in the figure is a switchgearinstalled in the U-phase (V-phase, W-phase) circuit. The switchgear 1 a(1 b, 1 c) is used for breaking electrically the current flow in theU-phase (V-phase, W-phase).

[0023] The disconnecting switch 2 a (2 b, 2 c) is connected to thetransformer side of the switch gear 1 a (1 b, 1 c). The disconnectingswitch 2 a (2 b, 2 c) isolates electrically the U-phase circuit into thegenerator-side circuit and the transformer-side circuit. Thegenerator-side circuit is a circuit located between the switchgear 1 a(1 b, 1 c) and the power generator, and corresponds to the circuitincluding the switchgear 1 a (1 b, 1 c). The transformer-side circuit isa circuit located between the switchgear 1 a (1 b, 1 c) and thetransformer, and corresponds to the circuit excluding the switchgear 1 a(1 b, 1 c).

[0024] The earthing switch 3 a (3 b, 3 c) and the arrester 4 a (4 b, 4c) are connected electrically to the transformer-side of thedisconnecting switch 2 a (2 b, 2 c). The earthing switch 3 a (3 b, 3 c)is used for reducing the circuit voltage at the transformer-side down tothe earthing electric potential and one of its terminal is grounded. Thearrester 4 a (4 b, 4 c) is used for regulating the overvoltagetransferred to the circuit for U-phase (V-phase, W-phase), and its oneterminal is grounded.

[0025] The earthing switch 5 a (5 b, 5 c) is connected electrically tothe transformer-side of the disconnecting switch 1 a (1 b, 1 c). Theearthing switch 5 a (5 b, 5 c) is used for reducing the circuit voltageat the generator-side down to the earthing electric potential and one ofits terminal is grounded.

[0026] One terminal of the primary side of the instrumentationtransformer 6 a is connected electrically to the generator-side of thedisconnecting switch 1 a. The other terminal of the primary side of theinstrumentation transformer 6 b and one of the primary side of theinstrumentation transformer 6 c are connected electrically to thegeneration-side of the disconnecting switch 1 b. The other terminal ofthe primary side of the instrumentation transformer 6 d is connectedelectrically to the generation-side of the disconnecting switch 1 c.

[0027] The other terminal of the primary side of the instrumentationtransformer 6 a is connected electrically in series connection to oneterminal of the primary side of the instrumentation transformer 6 b. Theother terminal of the primary side of the instrumentation transformer 6c is connected electrically in series connection to one terminal of theprimary side of the instrumentation transformer 6 d.

[0028] The instrumentation transformers 6 a to 6 d are used formeasuring the circuit voltage of U-phase to W-phase, and are composedwith open-delta connection.

[0029] Though not shown in this figure, a feeding disconnecting switchis connected electrically to the generator-side of the disconnectingswitches 1 a to 1 c. The instrumentation transformers for thedisconnecting switches 2 a to 2 c are connected to the transformer-sideof the disconnecting switches 1 a to 1 c.

[0030] FIGS. 1 to 3 illustrate the structure of the switchgearimplemented with the three-phase connection diagram shown in FIG. 4. Acomponent 10 in the figure is a base pedestal. A storage space islocated above the base pedestal 10. Link mechanism parts 12 a to 12 care contained in the storage space 13, which are connected mechanicallythrough the coupling rod 11 to the manipulator (not shown). Amanipulator box 14 is installed on the top and edge of the base pedestal10 and at one end side of the storage space 13. The manipulator is usedfor making the contact makers of the disconnecting parts of thedisconnecting switches 1 a to 1 c contacted and released on the block.The manipulator box 14 is taller than the storage space 13.

[0031] Containers 15 a to 15 c are arranged in the extended direction ofthe coupling rod 11 above the storage space 13. The width of theindividual containers 15 a to 15 c is defined to be identical to eachother, and the depth of the individual containers 15 a to 15 c isdefined to be identical to each other. Its width is smaller than itsdepth. The width of the container is defined as the dimension of thecontainer measured in the extended direction of the coupling rod 11. Thedepth of the container is defined as the dimension of the containermeasured in the vertical direction with respect to the extendeddirection of the coupling rod 11. The height of the container 15 a isdefined to be the same as the height of the container 15 c. The heightof the container 15 b is defined to be higher than the height of thecontainers 15 a and 15 c.

[0032] The container 15 a (15 b, 15 c) is composed of a base plate 16 a(16 b, 16 c), a side wall 17 a (17 b, 17 c) and a roof 18 a (18 b, 18c), and thus forms a gable-roof shaped box. The container 15 a (15 b, 15c) is made of metal, and made grounded. A gable-roof shape is such ashape of roof as a couple of plates are coupled to each other and as itsside projection looks like “

”, one of Japanese Hiragana characters. A gable-roof shaped box means abox having a gable roof.

[0033] A ceiling board 19 a (19 b, 19 c) is installed at the roof side18 a (18 b, 18 c) of the side wall 17 a (17 b, 17 c). The ceiling board19 a (19 b, 19 c) is used for supporting the pendant instrumenttransformer and arrestor as described later. A container box 20 a (20 b,20 c) is installed below the under surface of the base plate 16 a (16 b,16 c). The container box 20 a (20 b, 20 c) is used for containing thelink mechanism 12 a (12 b, 12 c) extended down below the base plate 16 a(16 b, 16 c).

[0034] An insulating tube 21 a for coupling between the container 15 aand the container 15 b is installed between the side wall 17 a and theside wall 17 b. An insulating tube 21 b for coupling between thecontainer 15 b and the container 15 c is installed between the side wall17 b and the side wall 17 c. The insulating tubes 21 a ad 21 b are usedas wiring ducts for routing the primary side lead wires for theinstrumentation transformer to be described later, from the container 15b to the containers 15 a and 15 c.

[0035] The breaker part 22 a (22 b, 22 c) of the disconnecting switch 1a (1 b, 1 c) is installed within the container 15 a (15 b, 15). Thebreaker part 22 a (22 b, 22 c) is enclosed by the main circuit conductor23 a (23 b, 23 c), the main circuit conductor 24 a (24 b, 24 c) and theinsulating member 25 a (25 b, 25 c), which is formed by arranging theswitching mechanism part 26 a (26 b, 26 c) at the part where theinsulating gas such as sulfur hexafluoride (SF6) are filled.

[0036] The main circuit conductor 24 a (24 b, 24 c) and the main circuitconductor 24 a (24 b, 24 c) are cylindrical members having electricconductivity. The main circuit conductor 24 a (24 b, 24 c) is insulatedand supported by the insulating and supporting member 27 a (27 b, 27 c)fixed at the base plate 16 a (16 b, 16 c). The main circuit conductor 24a (24 b, 24 c) is insulated and supported by the insulating andsupporting member 28 a (28 b, 28 c) fixed at the base plate 16 a (16 b,16 c).

[0037] The insulating member 25 a (25 b, 25 c) is a cylindrical memberformed between the main circuit conductor 23 a (23 b, 23 c) and the maincircuit conductor 24 a (24 b, 24 c), which is used for insulatingelectrically the main circuit conductor 23 a (23 b, 23 c) from the maincircuit conductor 24 a (24 b, 24 c), and vice versa.

[0038] The switching mechanism part 26 a (26 b, 26 c) is composed of thefixed switching mechanism part 29 a (29 b, 29 c) and the movableswitching mechanism part 30 a (30 b, 30 c). The fixed switchingmechanism part 29 a (29 b, 29 c) is fixed on the surface of the flangestanding out from the peripheral surface of the breaker part 23 a (23 b,23 c) to its inside in the radial direction, and a stick and fixedcontact maker is installed on its central axis. the movable switchingmechanism part 30 a (30 b, 30 c) is fixed on the surface of the flangestanding out from the peripheral surface of the breaker part 24 a (24 b,24 c) to its inside in the radial direction so as to face in an opposedposition to the fixed switching mechanism part 29 a (29 b, 29 c). At thecenter part of the movable switching mechanism part 30 a (30 b, 30 c), amovable contact maker is installed so as to be enable to contact to andleave from the fixed contact maker of the fixed switching mechanism part29 a (29 b, 29 c).

[0039] One side of the link mechanism 12 a (12 b, 12 c) is connectedmechanically to the movable contact maker of the movable switchingmechanism part 30 a (30 b, 30 c) at its opposite side to the fixedswitching mechanism part 29 a (29 b, 29 c). The link mechanism 12 a (12b, 12 c) is formed as a unit of mechanical components coupledmechanically to one another such as insulating rod, revolving shaftlever and operation rod, which reaches the inside of thecurrent-carrying conductor 27 a (27 b, 27 c) from the inside of thecontainer box 20 a (20 b, 20 c) through the hollow part formed in theinsulating and supporting member 28 a (28 b, 28 c). Hexafluoride (SF6)gas as the insulating gas is filled in the hollow part of the insulatingand supporting member 28 a (28 b, 28 c) and the inside of the containerbox 20 a (20 b, 20 c).

[0040] The switchgear 1 a (1 b, 1 c) in this embodiment is configured asa puffer so that the arc generated when opening the movable contactmaker from the fixed contact maker may be extinguished by spraying thecompressed hexafluoride gas used as insulating material at the breakerpart 22 a (22 b, 22 c).

[0041] The switching part 31 a (31 b, 31 c) of the disconnecting switch2 a (2 b, 2 c) is placed on the coaxial line shared by the breaker part22 a (22 b, 22 c) of the disconnecting switch 1 a (1 b, 1 c). Theswitching part 31 a (31 b, 31 c) is formed by arranging the switchingmechanism part 34 a (34 b, 34 c) at the area enclosed by the maincircuit conductor 24 a (24 b, 24 c), the main circuit conductor 32 a (32b, 32 c) and the insulating member 25 a (25 b, 25 c). The switchingmechanism part 34 a (34 b, 34 c) is insulated by air not like theswitching mechanism part 26 a (26 b, 26 c) of the breaker part 22 a (22b, 22 c).

[0042] The main circuit conductor 32 a (32 b, 32 c) is a conductivemember shaped in a cylinder. The main circuit conductor 32 a (32 b, 32c) is insulated and supported by the insulation and supporting member 35a (35 b, 35 c) fixed at the base plate 16 a (16 b, 16 c). The insulatingmember 33 a (33 b, 33 c) is a member shaped in a cylinder installedbetween the main circuit conductor 24 a (24 b, 24 c) and the maincircuit conductor 32 a (32 b, 32 c), and is used for insulatingelectrically between the main circuit conductor 24 a (24 b, 24 c) andthe main circuit conductor 32 a (32 b, 32 c).

[0043] The switching mechanism part 34 a (34 b, 34 c) is composed of thefixed switching mechanism part 36 a (36 b, 36 c) and the movableswitching mechanism part 37 a (37 b, 37 c). The fixed switchingmechanism part 36 a (36 b, 36 c) is connected electrically to the maincircuit conductor 24 a (24 b, 24 c) and has a fixed contact maker. Themovable switching mechanism part 37 a (37 b, 37 c) is on the surface ofthe flange standing out from the peripheral surface of the main circuitconductor 32 a (32 b, 32 c) to its inside in the radial direction so asto be opposed to the fixed switching mechanism part 36 a (36 b, 36 c).The central part of the movable switching mechanism part 37 a (37 b, 37c) contains a movable contact maker configured so as to be enabled tocontact to and leave from the fixed contact maker of the fixed switchingmechanism part 36 a (36 b, 36 c) in the horizontal direction.

[0044] One side of the link mechanism 38 a (38 b, 38 c) is connectedmechanically to the movable contact maker of the movable switchingmechanism part 37 a (37 b, 37 c) at its opposite side to the fixedswitching mechanism part 38 a (38 b, 38 c). The link mechanism 38 a (38b, 38 c) is formed as a unit of mechanical components coupledmechanically to one another such as insulating rod, revolving shaftlever and operation rod. The other side of the link mechanism 38 a (38b, 38 c) extends below the base plate 16 a (16 b, 16 c), and isconnected mechanically to the manipulator (not shown) for thedisconnecting switch, contained in the container box 13.

[0045] The fixed contact maker 40 a (40 b, 40 c) of the earthing switch5 a (5 b, 5 c) is connected electrically to the main circuit conductor23 a (23 b, 23 c) through the conductive member 39 a (39 b, 39 c). Themovable contact maker 41 a (41 b, 41 c) installed so as to be enabled tocontact to and leave from the fixed contact maker 40 a (40 b, 40 c) isplaced below the fixed contact maker 40 a (40 b, 40 c) in the verticaldirection and at the opposed position to the fixed contact maker 40 a(40 b, 40 c). A pair of the fixed contact maker 40 a (40 b, 40 c) andthe movable contact maker 41 a (41 b, 41 c) forms the switching part 42a (42 b, 42 c) of the earthing switch 5 a (5 b, 5 c). The movablecontact maker 41 a (41 b, 41 c) is operated by the manipulator (notshown) for the earthing switch contained in the container box 13.

[0046] The fixed contact maker 44 a (44 b, 44 c) of the feedingdisconnecting switch is connected electrically to the main circuitconductor 23 a (23 b, 23 c) through the conductive member 43 a (43 b, 43c). The movable contact maker 45 a (45 b, 45 c) installed so as to beenabled to contact to and leave from the fixed contact maker 44 a (44 b,44 c) is placed below the fixed contact maker 44 a (44 b, 44 c) in thevertical direction and at the opposed position to the fixed contactmaker 44 a (44 b, 44 c). A pair of the fixed contact maker 44 a (44 b,44 c) and the movable contact maker 45 a (45 b, 45 c) forms theswitching part 46 a (46 b, 46 c) of the feeding disconnecting switch.The movable contact maker 45 a (45 b, 45 c) is operated by themanipulator (not shown) for the feeding disconnecting switch containedin the container box 13.

[0047] The fixed contact maker (not shown) of the earthing switch 3 a (3b, 3 c) is connected electrically to the main circuit conductor 32 a (32b, 32 c) through the conductive member (not shown). The movable contactmaker (not shown) installed so as to be enabled to contact to and leavefrom the fixed contact maker is placed below the fixed contact maker inthe vertical direction and at the opposed position to the fixed contactmaker. A pair of the fixed contact maker and the movable contact makerforms the switching part of the earthing switch 3 a (3 b, 3 c). Themovable contact maker is operated by the manipulator (not shown) for theearthig switch contained in the container box 13.

[0048] At one side of the ceiling board 19 a (19 b, 19 c) (at the sideof the switching part 31 a (31 b, 31 c) of the disconnecting switch 2 a(2 b, 2 c)), the instrumentation transformer 47 a (47 b, 47 c) and thearrester 4 a (4 b, 4 c) are arranged along the line on which thecontainers 15 a to 15 c are installed. The instrumentation transformer47 a (47 b, 47 c) and the arrester 4 a (4 b, 4 c) are supported so as tobe suspended down from the ceiling board 19 a (19 b, 19 c). Theinstrumentation transformer 47 a (47 b, 47 c) is used for measuring thecircuit voltage of U-phase (V-phase, W-phase) used for operating theswitching part 33 a (33 b, 33 c) of the disconnecting switch 2 a (2 b, 2c), and its primary lead line is connected electrically to the connector48 a (48 b, 48 c) formed at the main circuit conductor 32 a (32 b, 32c). The arrester 4 a (4 b, 4 c) is used for regulating the overvoltageto be propagated to the circuit of U-phase (V-phase, W-phase).

[0049] The instrumentation transformers 6 a to 6 d are installed at theother side of the ceiling board 19 b (at the side of the breaker part 1b of the switchgear 1 b). The instrumentation transformers 6 a to 6 dare arranged lengthwise and breadthwise in two columns so as to besuspended from the ceiling board 19 b. The instrumentation transformers6 a to 6 d are used for measuring the circuit voltage of U-phase toW-phase to be used for operating the breaker part 22 a (22 b, 22 c) ofthe disconnecting switch 1 a (1 b, 1 c). The instrumentationtransformers 6 a to 6 d are composed of the core part having the primarywinding and the secondary winding and insulated by the insulating gas orthe insulating oil, and four conductive terminals extending down belowthe core part and insulated by the insulating material such as epoxyresin. Two of four conductive terminals form the primary-side terminalsand the rest of the conductive terminals form the secondary-sideterminals.

[0050] The primary-side lead line 49 connected electrically to one sideof the primary-side terminal of the instrumentation transformer 6 a isrouted from the inside of the container 15 b through the insulating tube21 a to the inside of the container 15 a, and is connected electricallyto the terminal 52 a installed in the main circuit conductor 23 a. Theother side of the primary-side terminal of the instrumentationtransformer 6 a and one side of the primary-side terminal of theinstrumentation transformer 6 b are connected electrically in seriesconnection. Though not shown in the figure, the primary-side lead line49 is supported by the insulating support member mounted at the ceilingboard 19 a.

[0051] The primary-side lead line 51 connected electrically to one sideof the primary-side terminal of the instrumentation transformer 6 d isrouted from the inside of the container 15 b through the insulating tube21 b to the inside of the container 15 c, and is connected electricallyto the terminal 52 c installed in the main circuit conductor 23 c. Theother side of the primary-side terminal of the instrumentationtransformer 6 d and one side of the primary-side terminal of theinstrumentation transformer 6 c are connected electrically in seriesconnection. Though not shown in the figure, the primary-side lead line51 is supported by the insulating support member mounted at the ceilingboard 19 c.

[0052] The primary-side lead line 50 connected electrically to the otherside of the primary-side terminal of the instrumentation transformer 6 band to one side of the primary-side terminal of the instrumentationtransformer 6 c is connected electrically to the terminal 52 b installedin the main circuit conductor 23 b. The secondary-side lead line (notshown) connected electrically to the secondary-side terminal of theinstrumentation transformers 6 a to 6 d is connected electrically to theinstrumentation device.

[0053] According to the above described embodiment, as theinstrumentation transformers 6 a to 6 d are arranged within thecontainer 15 b which is located in the midst of the center among thecontainers 15 a to 15 c arranged together, the installation operation ofthe instrumentation transformers 6 a to 6 d into the containers and thewithdrawal operation of the instrumentation transformers 6 a to 6 d fromthe containers may be applied only to the container 15 b, and theinstallation and withdrawal operation at the other containers may bedone simply by wiring the primary-side lead lines. Owing to thisconfiguration, the work load and work time for the installationoperation of the instrumentation transformers 6 a to 6 d into thecontainers and the withdrawal operation the instrumentation transformers6 a to 6 d from the containers can be reduced to a large extent, whichmay leads to an increase in the working efficiency for the installationoperation of the instrumentation transformers 6 a to 6 d into thecontainers and the withdrawal operation the instrumentation transformers6 a to 6 d from the containers. Thus, the working efficiency for theassembly operation of the switchgear and the replacement operation ofthe instrumentation transformers 6 a to 6 d can be increased.

[0054] The installation operation of the instrumentation transformers 6a to 6 d into the containers is performed as follows. At first, theinstrumentation transformers 6 a to 6 d are made mounted on the ceilingboard 19 b. Next, the ceiling board 19 b is made lifted by the crane,and mounted at the side wall 17 b of the container 19 b. Then, thewiring operation for the primary-side lead lines are performed for thecontainers 15 a to 15 c. The removal operation of the instrumentationtransformers 6 a to 6 d from the containers is performed by applying theabove installation procedures in reverse order.

[0055] According to this embodiment, the primary-side lead line 49connected electrically to the primary-side terminal of theinstrumentation transformer 6 a and the primary-side lead line 51connected electrically to the primary-side terminal of theinstrumentation transformer 6 d can be routed easily from the container15 b to the containers 15 a and 15 d. In case that the instrumentationtransformers are installed within the containers 15 a and 15 c, thereoccurs such a part that a couple of primary-side lead lines connectedelectrically to the primary-side of the instrumentation transformer arerequired to be routed, which leads to increasing the complexity of cablerouting or to upsizing the containers. In this embodiment, on thecontrary, as the instrumentation transformers 6 a to 6 d are installedwithin the container 15 b, a single cable routed from the container 15 bto the containers 15 a and 15 c can accommodate the primary-side leadline 49 connected electrically to the primary-side terminal of theinstrumentation transformer 6 a and the primary-side lead line 51connected electrically to the primary-side terminal of theinstrumentation transformer 6 d, which leads to reducing the complexityof cable routing or to downsizing the containers. Thus, the economicalefficiency of the switchgear can be increased.

[0056] According to this embodiment, as the insulating tube 21 a islinked between the container 15 a and the container 15 b and theinsulating tube 21 a is linked between the container 15 b and thecontainer 15 c, cyclic currents do not flow among the containers. Owingto this configuration, it will be appreciated that the heat build-up atthe containers 15 a to 15 c can be reduced. Thus, the safety of theswitchgears can be increased.

[0057]FIG. 7 shows a three-phase connection diagram of the switchgear inthe second embodiment of the present invention. In this embodiment, theinstrumentation transformers 7 a to 7 d are used for measuring thecircuit voltage of U-phase to W-phase, and their primary-side iscomposed with star-connection. The component parts identical to those inthe previous embodiment have like numbers and their detail descriptionis not repeated here.

[0058] One terminal of the primary side of the instrumentationtransformer 7 a is connected electrically to the generator-side of thedisconnecting switch 1 a. One terminal of the primary side of theinstrumentation transformer 6 c is connected electrically to thegeneration-side of the disconnecting switch 1 b. one terminal of theprimary side of the instrumentation transformer 6 e is connectedelectrically to the generation-side of the disconnecting switch 1 c.

[0059] The other terminal of the primary side of instrumentationtransformer 7 a and one terminal of the primary side of the primary sideof instrumentation transformer 7 b are connected electrically in series.The other terminal of the primary side of instrumentation transformer 7c and one terminal of the primary side of the primary side ofinstrumentation transformer 7 d are connected electrically in series.The other terminal of the primary side of instrumentation transformer 7e and one terminal of the primary side of the primary side ofinstrumentation transformer 7 d are connected electrically in series.The other terminal of the primary side of instrumentation transformer 7b and the other terminal of the primary side of the primary side ofinstrumentation transformer 7 d, and the other terminal of the primaryside of the primary side of instrumentation transformer 7 f areconnected electrically in series.

[0060]FIG. 5 and FIG. 6 illustrate the structure of the switchgearimplemented with the three-phase connection diagram shown in FIG. 7. Thecomponent parts identical to those in the previous embodiment have likenumbers and their detail description is not repeated here. In thisembodiment, as in the previous embodiment, the instrumentationtransformers 7 a to 7 f are mounted at the other side (at the breakerpart 22 a side of the disconnecting switch 1 a) of the ceiling board 19b within the container 15 b.

[0061] The instrumentation transformers 7 a to 7 f are used formeasuring the circuit voltage of U-phase to W-phase to be used foroperating the breaker part 22 a (22 b, 22 c) of the disconnecting switch1 a (1 b, 1 c), and are arranged in two columns lengthwise for thecontainer 15 d and in three columns breadthwise for the container 15 soas to be suspended from the ceiling board 19 b. The instrumentationtransformers 7 a to 7 d are composed of the core part having the primarywinding and the secondary winding and insulated by the insulating gas orthe insulating oil, and two conductive terminals (primary-sideterminals) and two secondary-side terminals extending down below thecore part and insulated by the insulating material such as epoxy resin.

[0062] The primary-side lead line 53 connected electrically to one sideof the primary-side terminal of the instrumentation transformer 7 a isrouted from the inside of the container 15 b through the insulating tube21 a to the inside of the container 15 a, and is connected electricallyto the terminal 52 a installed in the main circuit conductor 23 a. Theother side of the primary-side terminal of the instrumentationtransformer 7 a and one side of the primary-side terminal of theinstrumentation transformer 7 b are connected electrically in seriesconnection. Though not shown in the figure, the primary-side lead line53 is supported by the insulating support member mounted at the ceilingboard 19 a.

[0063] The primary-side lead line 54 connected electrically to one sideof the primary-side terminal of the instrumentation transformer 7 c isconnected electrically to the terminal 52 b installed in the maincircuit conductor 23 b. The other terminal of the primary side ofinstrumentation transformer 7 c and one terminal of the primary side ofthe primary side of instrumentation transformer 7 d are connectedelectrically in series.

[0064] The primary-side lead line 55 connected electrically to one sideof the primary-side terminal of the instrumentation transformer 7 e isrouted from the inside of the container 15 b through the insulating tube21 b to the inside of the container 15 c, and is connected electricallyto the terminal 52 c installed in the main circuit conductor 23 c. Theother side of the primary-side terminal of the instrumentationtransformer 7 e and one side of the primary-side terminal of theinstrumentation transformer 7 f are connected electrically in seriesconnection. Though not shown in the figure, the primary-side lead line55 is supported by the insulating support member mounted at the ceilingboard 19 c.

[0065] The other side of the primary-side terminal of theinstrumentation transformer 7 b the other side of the primary-sideterminal of the instrumentation transformer 7 d and the other side ofthe primary-side terminal of the instrumentation transformer 7 f areconnected electrically in series connection. The secondary-side leadline (not shown) connected electrically to the secondary-side terminalof the instrumentation transformers 6 a to 6 d is connected electricallyto the instrumentation device.

[0066] According to the above described embodiment, as theinstrumentation transformers 7 a to 7 f are arranged within thecontainer 15 b which is in the midst of the center among the container15 a to 15 c, the working efficiency for the installation operation ofthe instrumentation transformers 7 a to 7 f into the containers and thewithdrawal operation of the instrumentation transformers 7 a to 7 f fromthe containers maybe increased. Thus, the working efficiency for theassembly operation of the switchgear and the replacement operation ofthe instrumentation transformers 7 a to 7 f can be increased.

[0067] In addition, according to this embodiment, as the instrumentationtransformers 7 a to 7 f are installed within the container 15 b, asingle cable routed from the container 15 b to the containers 15 a and15 c can accommodate the primary-side lead line 53 connectedelectrically to the primary-side terminal of the instrumentationtransformer 7 a and the primary-side lead line 55 connected electricallyto the primary-side terminal of the instrumentation transformer 6 e,which leads to reducing the complexity of cable routing or to downsizingthe containers. Thus, the economical efficiency of the switchgear can beincreased.

[0068] According to the present invention, as the working load andworking time for the installation operation of the instrumentationtransformers into the containers and the withdrawal operation of theinstrumentation transformers from the containers can be reduced to alarge extent, the working efficiency for the installation operation ofthe instrumentation transformers into the containers and the withdrawaloperation of the instrumentation transformers from the containers can beincreased. Thus, the working efficiency for the assembly operation ofthe switchgear and the replacement operation of the instrumentationtransformers can be increased. In addition, according to the presentinvention, as the complexity of cable routing or the upsizing of thecontainers can be reduced, the economical efficiency of the switchgearcan be increased. The routing of the primary-side lead lines of theinstrumentation transformers can be accommodated in a single cableindependently upon the connection method for the primary-side lead linesof the instrumentation transformers.

What is claimed is:
 1. A switchgear installed in a main circuit from apower generator to a transformer and structured in a phase-separationconfiguration, comprising three containers arranged together; adisconnecting switch having a breaker part disconnecting said maincircuit electrically and insulated by an insulating gas, said breakerpart arranged in each of said three containers, and a manipulator formaking contact to and leaving from a contact maker of said breaker part;and plural instrumentation transformers for measuring a voltage of saidmain circuit, wherein said plural instrumentation transformers areinstalled in a container located in a midst among said three containers.2. A switchgear installed in a main circuit from a power generator to atransformer and structured in a phase-separation configuration,comprising three containers arranged together; a disconnecting switchhaving a breaker part disconnecting said main circuit electrically andinsulated by an insulating gas, said breaker part arranged in each ofsaid three containers, and a manipulator for making contact to andleaving from a contact maker of said breaker part; and pluralinstrumentation transformers for measuring a voltage of said maincircuit, wherein a couple of coadjacent containers among said threecontainers are linked by an insulating tube; said plural instrumentationtransformers are installed inside a container located in amidst amongsaid three containers; a primary-side lead line for an instrumentationtransformer corresponding to a phase for an container located in eitherof both ends among said three containers is routed from a containerlocated in a midst among said three containers through said insulatingtube into a corresponding container located in either of both ends.
 3. Aswitchgear installed in a main circuit from a power generator to atransformer and structured in a phase-separation configuration,comprising three containers arranged together; a disconnecting switchhaving a breaker part disconnecting said main circuit electrically andinsulated by an insulating gas, said breaker part arranged in each ofsaid three containers, and a manipulator for making contact to andleaving from a contact maker of said breaker part; pluralinstrumentation transformers for measuring a voltage of said maincircuit, a switching part of a disconnecting switch and an earthingswitch connected electrically to said main circuit and arranged in eachof said three containers; and an arrester; wherein a couple ofcoadjacent containers among said three containers are linked by aninsulating tube; said plural instrumentation transformers are installedinside a container located in a midst among said three containers; aprimary-side lead line for an instrumentation transformer correspondingto a phase for an container located in either of both ends among saidthree containers is routed from a container located in a midst amongsaid three containers through said insulating tube into a correspondingcontainer located in either of both ends.
 4. A switchgear claimed ineither of claims 1 to 3, wherein a primary-side of said pluralinstrumentation transformers is configured with an open-delta connectionmethod or a start connection method.
 5. A switchgear claimed in eitherof claims 1 to 3, wherein the height of a container located in a midstamong said three containers is higher than that of two other containers.6. A switchgear claimed in either of claims 1 to 3, wherein said pluralinstrumentation transformers are supported so as to be suspended from aceiling board installed above said container.
 7. A switchgear claimed inclaim 3, wherein said arrester is supported so as to be suspended from aceiling board installed above said container.